batman-adv: Add multicast forceflood mesh genl configuration

The mesh interface can optimize the flooding of multicast packets based on
the content of the global translation tables. To disable this behavior and
use the broadcast-like flooding of the packets, forceflood has to be
enabled.

The BATADV_CMD_SET_MESH/BATADV_CMD_GET_MESH commands allow to set/get the
configuration of this feature using the
BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED attribute. Setting the u8 to zero
will disable this feature (allowing multicast optimizations) and setting it
to something else is enabling this feature (forcing simple flooding).
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>

include/uapi/linux/batman_adv.h

@@ -455,6 +455,15 @@ enum batadv_nl_attrs {
 	 */
 	BATADV_ATTR_LOG_LEVEL,
 
+	/**
+	 * @BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED: whether multicast
+	 *  optimizations should be replaced by simple broadcast-like flooding
+	 *  of multicast packets. If set to non-zero then all nodes in the mesh
+	 *  are going to use classic flooding for any multicast packet with no
+	 *  optimizations.
+	 */
+	BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED,
+
 	/* add attributes above here, update the policy in netlink.c */
 
 	/**

net/batman-adv/netlink.c

@@ -155,6 +155,7 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
 	[BATADV_ATTR_GW_SEL_CLASS]		= { .type = NLA_U32 },
 	[BATADV_ATTR_HOP_PENALTY]		= { .type = NLA_U8 },
 	[BATADV_ATTR_LOG_LEVEL]			= { .type = NLA_U32 },
+	[BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED]	= { .type = NLA_U8 },
 };
 
 /**
@@ -343,6 +344,12 @@ static int batadv_netlink_mesh_fill(struct sk_buff *msg,
 		goto nla_put_failure;
 #endif /* CONFIG_BATMAN_ADV_DEBUG */
 
+#ifdef CONFIG_BATMAN_ADV_MCAST
+	if (nla_put_u8(msg, BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED,
+		       !atomic_read(&bat_priv->multicast_mode)))
+		goto nla_put_failure;
+#endif /* CONFIG_BATMAN_ADV_MCAST */
+
 	if (primary_if)
 		batadv_hardif_put(primary_if);
 
@@ -564,6 +571,14 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info)
 	}
 #endif /* CONFIG_BATMAN_ADV_DEBUG */
 
+#ifdef CONFIG_BATMAN_ADV_MCAST
+	if (info->attrs[BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED]) {
+		attr = info->attrs[BATADV_ATTR_MULTICAST_FORCEFLOOD_ENABLED];
+
+		atomic_set(&bat_priv->multicast_mode, !nla_get_u8(attr));
+	}
+#endif /* CONFIG_BATMAN_ADV_MCAST */
+
 	batadv_netlink_notify_mesh(bat_priv);
 
 	return 0;